Last week, I queued up in cyberspace to drop the better part of a week’s pay on tickets to see U2 at the Rose Bowl in Pasadena, CA. Much like they did 30 years ago, U2 are selling out stadiums and playing songs from The Joshua Tree. For a band so wary of using nostalgia to remain relevant, taking The Joshua Tree on the road represents an unmistakable shift in the band’s thinking.